Control for aircraft superchargers



-May' 15, 1945. SIHQIULTS I 2,376,199

coNTRbL FOR AIRCRAFT SUPYERCHARGERS Filed March 31, 1942 2 Sheets-Sheet 1 P ig. l.

ALTITUDE Inventor: David R Shoulta b QLMAH, y fi s Attorney May 15, 1945. sHou s 2,376,199

CONTkOL FOR AIRCRAFT SUPERCHARGERS Filed March 31, 1942 2 Shee ts-Sheet 2 DR/ VEN FROM 641/ 58 GHARGER Fig.4. a

Inventof": David'RShoul'bs,

y Ii i ZAbt orfney.

' means embodying Patented May'15, 1945' CONTROL FOR AIBICRAFI SUPER-CHARGERS 1 David R. Shoults, Schenectady,

to General Electric Company,

' New York g N. Y., assignor a corporation of Application March 31,1942, Serial No. 431,991 I 1 Claim. ('01. ze -11) The present invention relates-to aircraft superchargers and particularly to control means therefor. It is especially applicable to superchargers of the type comprising a turbine wheel driven by exhaust gases from an aircraft engine, the turbine wheel driving a compressor which supplies air to the aircraft engine or to another point of consumption, such as a cabin. Such superchargers are termed usually turbo-superchargers.

In use, it is desired to control a turbo-supercharger so as to supply air at a constant desired i pressure or at a constant rate; of flow and to this end, governors responsive to pressure or responsive to rate of fiow have been provided, such governors acting directly on the regulatin means for the turbine, for example, a waste-gate valve.

However, the control of turbo-superchargers presents unusual problems and diillculties due to the relatively large number of varying factors met with in the maneuvering of an aircraft, and, up to the present time, so far as I am aware, no

1 wholly satisfactory control has been devised. To

besatisfactorya control must be stable and rejliablein operation and give protection to the supercharger against overspeed.

. The object of my invention is to provide an improved regulator for a turbo-supercharger, and for a consideration of what I believe to be novel a d my invention, attention is directed to the llowing specification and to the claims appended thereto.

In the drawings, Fig. of a turbo-supercharger. provided with a control my invention; Fig. 2 is a diagram; F18. 3 is a view sim'ilar'to Fig. 1 showing a modification embodying my invention, and Fig.

1 4 is a detail view of a further modification.

- Referring to the drawings, l indicates the tur bine wheel of a turbo-supercharger and '2 indicates the nozzle box. Exhaustgasesfrom an air-;

1 is a diagrammatic view somewhat higher than closed whereby craft engine are ppl ed to the nozzle box through a duit 3 which connects with the ex-' haust manifold of the engine. The nozzle box is provided with nozzles 4. which directexhaust gases from the nozzle box to the buckets of the turbine wheel for driving the wheel. Connected with" the nozzle box is a waste conduit 5 through which exhaust gases-may flow from the nozzle box directly to atmosphere; In conduit 5 is a waste-gatevalve 6 which forms the regulator or control means for the supercharger. The compressor of the supercharger is indicated at 1. Air

issupplied tothe compressor through .a central inlet 8 and is discharged through the conduit 9.

- Air-is supplied to inlet 8 usuallythrough a conhe understood manner.

to the forward movement of the aircraft, the air the impeller at a pressure atmospheric pressure due to the ram action as the air is forced through the conduit. Discharge conduit 9 may be connected to any suitable point of consumption. For example, the air may be used to supply combustion air to the engine or it may be used to super reaching the eye of charge a cabin.

The foregoing is to betaken as typical .of any suitable turbo-supercharger, the arrangement described being a known one. The regulation of the speed of the supercharger is effected by adjusting waste-gate valve 6. When the waste-gate valve is open, exhaust gases pass fromnozzle box 2 directly to atmosphere little if any passing through the turbine wheel so that at this time the compressor is idle. As wastegate valve 8 is moved toward closed position, are discharged to atmosphere and gases are then directed through the nozzles to the turbine wheel to operateit. Maximum output would be represented by waste-gate valve 6 being completely craft engine are directed to the turbine wheel.

According to my invention, I depart entirely from regulating arrangements heretofore used on gas driven superchargers for aircraft and place the regulator for .the supercharger, i. e., wastegate valve 6, directly under the control of a long range "speed governor driven from the supercharger shaft. By this-arrangement, the supercharger is controlled directly as, to speed. I then i provide in connection with the speed governor a means for setting thegovemor for different speeds of operation. This latter maybe accomplished in any suitable manner, such as byZloadinggthe governor spring, by adjusting a sleeve valve for the pilot valve of the servo-motor through which the governor actuates the waste-gate valve, or

by other suitable means, depending on the type of speed governor utilized in carrying out the invention.

In the present governor of the fiyball type but it is to be understood that my invention is not limited thereto necessarily. 9 I

Referring particularly to Fig. 1; lo indicates a speed governor which is driven from the super-' through suitable gearing in a well It may be a centrifugal govcharger' shaft fewer of the gases all available gases from the airinstance, I have shown a speedthat it has a range sufficiently long to meet the requirements of the particular control. In the present instance, I have elected to show a flyball governor of known type. The spindle IIof the governor projects into the pilot valve casing I 2 of a pilot valve and carries pilot valve heads I3. and

I4. Pilot valve heads I3and l4 control ports I 5' and I5 in a pilot valve sleeve I7 located in pilot valve casing I2 and adapted to slide longitudinally therein. In pilot valve sleeve I l is an inlet port I8 which communicateswith a fluid Dressure supply pipe I9 and discharge ports 20 and ZI which communicate with fluid discharge pipes 22 and 23. Pipe I9 may lead from any suitable source of operating fluid, for example, a'supply of oil of suitable pressure, and pipes 22 and 23 may lead to any suitable point of discharge. Ports I5 and I B are connected by conduits 24 and 25 to the cylinder 25 of the servo-motor on opposite sides of the servo-motor piston 21. In the inner wall of casing I 2 are elongated chambers through to waste-gate valve 6. At an intermediate point of lever 28 is a roller 33 which engages with the inclined or cam surface of a wedge-shaped cam member 34 carried on the end of a piston rod 35 connected to a piston 36 located in the cylinder 31 of a fluid actuated motor or servo-motor. Cyl inder 31 on opposite sides of piston 35 is connected by conduits 39 and to the casing of a pilot valve 4|. The fluid pressure inlet pipe for pilot valve 4| is indicated at 42 and the fluid pressure outlet pipes are indicated at 43 and 44. In the pilot valve casing are pilot valve heads 45 and 48 carried by pilot valve stem 41. This forms a known type of fluid actuated motor or servomotor. Pipe 42 may lead from any suitable fluid pressure supply and pipes43 and 44 may lead to any suitable discharge point.

Normally, pilot valve heads 45 and 46 cover the ends of conduits 39 and 40. The outer end of pilot valve stem 41 is pivotally connected to an intermediate point of a floating lever 48. One end of lever 48 is pivotally connected .to piston rod 35 and the other end is pivotally' connected by a link 49 to the central portion of a floating lever 50. One end of floating lever 50 is connected to a hand control lever 5| adjustable to fixed positions along a quadrant 52. Hand control lever 5I is located in reach of and sothat it can be positioned by the 50 is pivotally connected to the stem 53 of a Sylphon bellows 54. Bellows 54 is evacuated so ernor of any suitabletype, a requirement being Which-roller 33 is in engagement with the inclined surface of wedge-shaped member 34 bya spring 58 which surrounds spindle II and at one end engages the end of sleeve Iland at the other end engages a fixed abutment 59. By this arrangement, the sleeve is made to follow the movements of the wedge-shaped member.

The operation is as follows:

Assume that the aircraft on which the supercharger and its control is mounted is operating and that the supercharger is running. At this time, exhaust gases are being supplied from the engine to turbine wheel I to operate it, the turbine wheel driving the compressor to supply compressed air through conduit 9. Waste-gate valve Swill stand in an adjusted position to maintain the speed for which speed governor H3 is set. If the speed tends to increase, the weights of speed governor I0 will move outward against the action of the governor springs, effecting amovement of pilot valve heads I3 and I4 toward the v right in'Fig. 1 to uncover somewhat ports I5 and I6, thus admitting fluid pressure to the righth-and end of cylinder 26 through port I B and conduit 25, and permitting it to discharge from the left-hand end thereof through conduit 24 and port I5. This effects movement of piston 27 in a lefthand direction, thus opening somewhat the waste-gate valve to permit a greater percentage of exhaust gases to pass directly to atmosphere so that fewer gases are supplied to turbine wheel I whereby the speed of the wheel decreases. When piston 2'! moves toward the left, it moves the upper end of lever 28 toward th left, thus moving pilot valve sleeve I1 toward the right until ports I5' and I3 are again covered by pilot valve heads I3 and I4. If the speed of the supercharger decreases, the speed governor moves stem seen that speed governor I0 operates the wasteaircraft operator. The other end of floating lever gate valve through a servo-motor, including a follow-up device or connection. The speed governor thus maintains thesupercharge'r' operating at a substantially constant speed; and at, such constant speed, other factors remaining constant, it will deliver air at a constant pressure. The supercharger is under the direct control of a restored speed governor, a type of governor which is sensitive but which at the same time has stable operating characteristics.

If we assume now that the aircraft ascends to ,a higher altitude, then pressure evacuated bellows 54 will be distended by spring-55 and through stem 53 and floating lever 50, link 49 will lower the left-hand end of floating lever 48,.thus moving downward pilot valve heads 45 and 46. Fluid pressure will be admitted from the pilot valve through conduit 40 to the lower end of cylinder 31 which will eifect an upward movement of the I piston 35 and hence of wedge-shaped member 3%,

the fluid above piston 36 being discharged right, floatin -ton rod' 29. w

' any time, he can do so by will deliver air to the engine at a pressure to give through conduit 39 and discharge pipe 43. The upward movement of piston 38 hits the right-. hand endor floating lever 48 and restores pilot valve heads 45 and 45 to position where they again cover the ends of conduits 38 and 46. Upward movement of wedge-shaped member 34 serves to move pilot valve sleeve II tdward the ever "pivoting on the end of pisereby fluid pressure is admitted through the pilot valve to the left-hand end of cylinder 25, thus moving piston 21 in a direction to effect a closing movement of waste-gate valve 6. This serves to increase the speed of the supercharger, the speed increasing until speed governor l movespilot valve heads l3 and I4 to the right sufllciently to again cover ports l5 and IS; The governor is thus set for a higher speed and will maintain the supercharger at that speed. The arrangement is such that the increase in speed at the higher altitude will be sumcient to give the desired pressure on the discharge side of the compressor.

what to effect the operation just described exam in the opposite direction to lower the speed of the supercharger to.the value desired for' the correrect control of the waste-gate valve.

If the aircraft operator desires to effect adjustment oi the, setting of. the speed governor at moving hand lever 5| along the quadrant 52. In the arrangement shown, movement of the hand lever 5| in a clockwise direction serves to lower pilot valve heads 45 and 46 in the pilot valve casing, thus effecting an upward movement of piston 36 in cylinder 31, and movement of pilot valve sleeve ll in a righthand direction and hence a setting .of the speed governor for a higher speed. Movement of hand lever 5| in an anti-clockwise direction in a simiposition of bellows 54 It the aircraft descends to a lower altitude, then bellows 54 is collapsed some lar way efi'ects setting of speed govemor'lfl for Referring to Fig. 2, wherein the abscissas reppresent altitude and the ordinates speed of the supercharger in revolutions per minute, hand lever 5| may be set so that .at altitude a the speed governor will be set to maintain speed b. Then the bellows 54 and the mechanism. through which it operates sleeve, may be so designed and adjusted that as the aircraft ascends the speed will be increased along the line c'until the maximum permissible speed for the supercharger is reachedv at t e point d, which may represent the critical alti de; l. e. the rated altitude of the supercharger, .At this time, the bellows will have reached its stop 58 so that the speed will then remain constant along the ,line a as the aircraft charger, i. e., to supercharger pressure.

. lows 65.

lever '72 which corresponds to handlever 5| of ascends to higher altitudes. ,From point b to point d-there will be maintained a definite speedaltitude relationship. The relationship may be so .'set that for each altitude up to critical altitude,

the speed of the supercharger will be such that it will deliver air at the desired pressure for that altitude. For example, in the case or supercharging an engine, the speed-altitude relationship may be such that for each altitude, the supercharger relationship willbe represented by a. line such as the broken line .f-g, while by moving hand lever 5| ,in ananti-clockwise direction, the governor may be set for a lower speed for a given position .of bellows 54 so that the speed-altitude relation ship-will be represented by a line such as the broken line h In Fig. 1, the control mechanism for setting the speed governor is responsive to'altitude absolute pressure alone. It may, however, be made responsive to other conditions pertinent to the operation of the supercharger. For example, it may be made responsive to a condition of the air discharged by the supercharger, such as the air discharge pressure or the rate of air flow; to a condition of the gases supplied to the supercharger, i. e., nozzle box pressure, or to a condition 'of the aircraft engine; or it may be made responsive to various combinations of such conditions. In Fig. 3, by way of example, I have shown an arrangement wherein the setting of the governor is responsive to a combination of absolute atmospheric pressure and to the pressure of the air on the discharge side of the supercharger compressor. In Fig. 3, the same reference numerals the same as in Fig. 1 have been used to designate corresponding parts. In this arrangement, the left-hand end of floating, lever 52 corresponding to the lever 50 of Fig. 1 is pivotally connected to a stem 63 which at one end is fixed to the movable end of an evacuated bellows 64 and at the other end is fixed to the movable end of a bellows 65. Evacuated bellows 64 is carried by a fixed abutment 66 and is provided with a compression spring 61 which opposes collapsing of the bellows. It may be, in all respects similar to bellows 54 The stationary end of bellows 6% is fixed to a support 68 and has its interior connected by a pipe 69 to the discharge side of the supercharger compressor, i. e., to. conduit 9. Thus, the interior of bellows 65 is subjected to pressure on the discharge side or the super- Bellows 6 4 and 65 are in opposed relation to each other and are of the same diameter so that each is subjected to altitude atmospheric pressure to the same extent. As a result, bellows 54-55 provide a means responsive tothe absolute pressure on the discharge side 'of the compressor. Surrounding the bellows 65 is a rectangular frame -10, the upper cross-bar of which has an opening through which stem 63 passes loosely and which rests againstthe movable end of bel- Connected to the lower cross-bar of frame 10 is a spring 'II connected to a hand Fig. 1 and which may be positioned along a quadrant I3. By adjusting hand lever I2 along the quadrant 13, the eilective action or pull or spring H on bellows may be adjusted. Spring 'I-l acts in opposition to the pressure within bellows 65; in other words, bellows 55" tends to be collapsed by spring II and to-be extended by the supercharger pressure to& which its interior is. subjected. This arrangement or bellows B4 and 65 provides a device which is responsive to the absolute supercharger pressure, r

so that the speed-altitude The operation of the arrangement shown in Fig. 3 is obvious from the description given of the operation of the arrangement shown in Fig. 1. As the altitude of the aircraft changes, bellows 55 operates through floating lever 50 and the servo-motor to position wedge-shaped member 34 and adjust the setting of the speed governor.

Likewise, if the pressure on the discharge side of the supercharger varies, it will effect a movement of the bellows 65 to move the left-hand end zle box. This arrangement is indicated in Fig. 4.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with apparatu representing embodiments thereof but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by 5 Letters Patent of the United States, is:

In combination, an exhaust gas driven supercharger for aircraft, a regulating valve therefor, a long range speed governing mechanism for positioning the valve including a speed governor 10 driven from the supercharger, a servo motor for positioning the valve and a pilot valve for controlling the now of operating fluid to the servo motor and having a valve stem connected to the speed governor and a bushing connected by it; a follow-up lever to the servo motor, a variable fulcrum for thelever, and means for manually and automatically setting the speed governing mechanismfor difierent speeds comprising a hydraulic motor connected to the fulcrum, a pilot 20 valve for the hydraulic motor and means for manually and automatically positioning the last named pilot valve including a hand operated lever and a device responsive to changes of pressure appurtenant to the operation of the super- DAVID R. SHOULTS.

25 charger. 

